How to select product specification & payment option when admin creates order

Hi,

The options cannot be selected in the backend. You can add them separately to the order as another product.
For the characteristics/variants, you can directly select them on the products listing popup when you add products to the order.
For that, change the product type dropdown on the top right to "variants" or "both".

You can't place a payment for an order from the backend.

You could however alternatively do the order on your frontend with your own account and then change the user of the order in the backend after the payment.